Navigation systems for vehicles, motor vehicles in particular, and methods for operating such navigation systems are available. They are used to determine the instantaneous geographic position of the vehicle and, as a function of a specifiable destination to be reached, to calculate the most favorable itinerary and to give the driver instructions concerning the itinerary.
Such navigation systems require information, which is necessary to determine the instantaneous position of the vehicle and calculate the itinerary. In particular, this includes road routing, turning conditions, and the like. This data is provided in the form of a database. To this end, the database includes, for example, a digital road map containing landmarks and/or decision-making points of the possible routes. Providing the database in on-board mass storage devices, a CD-ROM, for example, is available.
Furthermore, a position-finding system that determines the instantaneous geographic position of the vehicle is necessary. The satellite-supported global position-finding system (GPS), for example, is available for this purpose.
An electronic data processing device compares the position data delivered by the position-finding system with the data stored in the digital road map and determines the instantaneous position of the vehicle. Corresponding to the selected destination, the electronic data processing device may provide route guidance information to the driver visually and/or acoustically on a selected most favorable itinerary using landmarks and/or decision-making points.
To perform the functions indicated, such navigation systems may be made up of functionally interconnected subsystems. Such individual subsystems include systems such as an electronic data processing device, position-finding system, digital road map, vehicle sensor system, communication module, obstacle calculation device, itinerary determination device, route guidance device, input unit, and output unit.
A disadvantage with such navigation systems and with available methods for operating navigation systems may be that if the driver allows himself to be guided by the navigation system, he may need to exclusively travel the route that is calculated by the navigation system and output to him as a route guidance instruction. If, according to his own discretion, the driver chooses another route to travel, which deviates from the route specified by the navigation system, he may not reasonably use the information from the navigation system because such navigation systems are not believed to be designed for this purpose. Therefore, the driver may not select a route for a segment familiar to him, which he has chosen based on personal criteria relating to length of time, traffic load, efficiency or preference, or use the navigation system when traveling this route.
For example, the driver may like to select a different route than the one calculated by the navigation system for the way from his home to his workplace and back. For this purpose also, certain information from the navigation system could be useful to him. Even if route guidance instructions are not necessary for this route because the driver knows it perfectly, he is still interested in obtaining timely information concerning the traffic situation in order to be able to travel another route if necessary if, for example, a traffic jam exists in the stretch of road still ahead of him in the route originally planned. However, the present methods for operating navigation systems and corresponding navigation systems may not allow the navigation system to output information concerning the traffic situation when traveling a route selected by the driver himself, which is not provided in the navigation system.